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Name:	us-gaap_ClassOfWarrantOrRightLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Summary of Warrant Activity (Parenthetical) (Detail) - shares	1 Months Ended		12 Months Ended
	Nov. 30, 2018	Apr. 30, 2018	Dec. 31, 2018
Class Of Warrant Or Right [Line Items]
Number of shares of warrants forfeited/cancelled		4,250	6,095
Healthcare Ventures VIII
Class Of Warrant Or Right [Line Items]
Number of shares of warrants forfeited/cancelled	1,845